While it is true that members of most sexually reproducing species can be defined as either male or female, those who belong to the rest of the biological world are not so simply understood. Hermaphroditic creatures reproduce both as male and as female individuals, providing a fascinating glimpse into alternative sexual practices in nature and their ecological and evolutionary successes and failures.
Eloquently written by an award-winning biologist and pioneer in molecular ecology, this primer on hermaphroditism traces the phenomenon throughout Earth's myriad species, accounting for the adaptive significance of alternative sexual systems. Accessible and richly illustrated, the text maps the evolutionary origins of hermaphroditism, as well as its historical instances and fictional representations, underscoring the relevance of dual sexuality to our biological, intellectual, and cultural making. John C. Avise describes the genetics, ecology, phylogeny, and natural history of hermaphroditic plants, fish, and invertebrate animals and details organisms that either reproduce simultaneously as male and female or switch routinely between one sex and the other. Filled with surprising creatures and compelling revelations, Hermaphroditism stands alone in its clear yet comprehensive treatment of hermaphroditism and its unique challenge to the supremacy of separate sexes.
The Phenomenon of Dual Sexuality
Hermaphroditism in Fiction
Hermaphroditism in the Real World
1. Two Sexes in One
Maleness and Femaleness
Anisogamy and the Separate-sex Condition
Sex Ratios in Separate-sex Taxa
Sex Ratios in Hermaphroditic Taxa
Hermaphroditism Versus Separate Sexes
2. Dual-sex Plants
Alternative Sexual Systems: Natural History and Examples
Cosexuality Versus Dioecy
Selfing Versus Outcrossing
Sexual Selection in Plants
3. Dual-sex Invertebrates
Sex Determination and Pseudohermaphroditism
Evolutionary Histories: Gonochorism and Hermaphroditism
Selfing Versus Outcrossing
Sex Allocation in Simultaneous Hermaphrodites
Sex Allocation in Sequential Hermaphrodites
Conclusions About Sex Allocation Theory
4. Dual-sex Vertebrates
Adaptive Significance of Alternative Modes
John C. Avise is Distinguished Professor of Ecology and Evolutionary Biology at the University of California, Irvine. He is an elected member of both the National Academy of Sciences and the American Academy of Arts and Sciences, and the author or editor of 20 books, including most recently Inside the Human Genome: A Case for Non-intelligent Design; Molecular Ecology and Evolution: The Organismal Side; and Clonality: The Genetics, Ecology, and Evolution of Sexual Abstinence in Vertebrate Animals.
"This book provides a basic, nontechnical introduction to sexual systems for a wide audience of readers."
"Avise's book is truly what is expected from a primer, and ought to be read by all researchers interested in hermaphroditism, perhaps even more botanists than zoologists."
– Philippe Jarne, The Quarterly Review of Biology
"Finally! [...] This new book, for the first time, assembles our state-of-the-art understanding of the biology of hermaphrodite gender expression, and makes the current research agenda on these fascinating organisms broadly accessible to both scientists and (under-)graduate students [...] "
– Nils Anthes, Ecology